The most critical part of a plant's life cycle for persisting in a warming climate

Background/Question/Methods

Climate warming is inducing many plant species to shift their ranges poleward in latitude or upward in elevation. Previously, we developed a mathematical model on an unstructured population, and showed that climate warming poses a pressure on population persistence. For example, a population may not persist if too many of its propagules are left behind by their shifting favorable habitat, and hence do not live to reproduce. We then asked: which stage transition in a plant's life cycle matters most in helping the population to persist? To answer this question, we extended the model to structured populations, applied it to plant species, and conducted sensitivity and elasticity analyses. For each plant, we parameterized the mathematical model, using published transition matrices and dispersal kernels. The relative importance of each stage transition is monitored through changes in sensitivity and elasticity values at increasing rates of climate warming (rate at which suitable climate spaces shifts in a one-dimensional space). 

Results/Conclusions

We present here results from these analyses on three species: teasel (Dipsacus sylvestris), nodding thistle (Carduus nutans), and Scotch broom (Cytisus scoparius). For teasel, for example, the transition from seeds to large rosettes becomes most import as the speed of climate warming increases. Thus, this species is pressured to be more biannual as opposed to perennial under climate warming. This is understandable: for a population pressed to keep up with spatial change, taking a shorter time to reach reproductive stage creates more opportunities for reproduction. Seeds that take longer to become reproductive have a higher chance of being left behind the shifting habitat.